Karl Alexander studied at the Universities of Strasbourg, Würzburg, and Mainz and then subsequently went on a European tour. In 1797, he was appointed successor to his ailing father's position as Prinzipalkommissar at the Immerwährender Reichstag (German: Perpetual Imperial Diet) in Regensburg. Karl Alexander also worked for the Thurn and Taxis postal empire, operating during a decline due to the gradual loss of territory as a result of the Napoleonic Wars.

[edit] Marriage and family

Karl Alexander married Duchess Therese of Mecklenburg-Strelitz, fourth eldest child and third eldest daughter of Charles II, Grand Duke of Mecklenburg and his wife Princess Friederike of Hesse-Darmstadt, on 25 May 1789 in Neustrelitz, Mecklenburg-Strelitz.[1][2] Karl Alexander and Therese had seven children:[1][2]